Out-of-bounds Read Affecting libXfont-devel package, versions <0:1.5.4-1.amzn2.0.2


Severity

Recommended
0.0
high
0
10

Based on Amazon Linux security rating.

Threat Intelligence

EPSS
0.26% (17th percentile)

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  • Snyk IDSNYK-AMZN2-LIBXFONTDEVEL-19457389
  • published1 Sept 2026
  • disclosed10 Sept 2026

Introduced: 1 Sep 2026

CVE-2026-59679  (opens in a new tab)
CWE-125  (opens in a new tab)

How to fix?

Upgrade Amazon-Linux:2 libXfont-devel to version 0:1.5.4-1.amzn2.0.2 or higher.
This issue was patched in ALAS2-2026-3890.

NVD Description

Note: Versions mentioned in the description apply only to the upstream libXfont-devel package and not the libXfont-devel package as distributed by Amazon-Linux. See How to fix? for Amazon-Linux:2 relevant fixed versions and status.

fs_read_glyphs() in the libXfont2 font-server client (src/fc/fserve.c) indexes the per-character encoding[] array using num_chars from the FS_QueryXBitmaps16 reply, but that array was allocated with a size derived from num_extents in the separate FS_QueryXExtents16 reply. The two CARD32 fields are never cross-checked. A malicious or compromised font server can send a small num_extents (e.g. 1) in the extents reply, then a large num_chars (e.g. 100000) in the bitmaps reply. This causes attacker-controlled out-of-bounds heap read and writes.

CVSS Base Scores

version 3.1